The present invention relates to a fixing member for fixing, inside of an electroluminescent (which will hereinafter be abbreviated as xe2x80x9cELxe2x80x9d) device, a removing agent of a predetermined gas component in the EL device; an EL device using the fixing member; and a backing substrate for the EL device.
For displays or light emitting elements of various apparatuses such as mobile apparatuses, EL devices have conventionally been used as an emitter. EL devices are however accompanied with such a drawback that luminous performances such as luminance and luminous uniformity are extremely deteriorated under high temperature conditions or with the passage of a predetermined time, compared with those at an initial stage. Such a deterioration in luminous performances is known to be caused by appearance of non-luminous portions (dark spots) inside of the EL device due to water adsorbed to the surface of a component part or component material of the EL device, or water or a gas such as oxygen or organic gas penetrated from the outside.
With a view to removing the above-described causes for deterioration of luminous performances (appearance of dark spots), proposed in JP-A-9-148066 (the term xe2x80x9cJP-Axe2x80x9d as used herein means an xe2x80x9cunexamined published Japanese patent application) is an EL device equipped inside thereof with drying means formed from a compound which chemically adsorbs water and at the same time, maintains a solid condition even if absorbing humidity. After solidification, the compound to be drying means is fixed inside of this device.
The above-described EL device, however, requires a step for solidifying the compound to be drying means, thereby needing time and equipment for solidification. It therefore involves the problem that a manufacturing cost becomes higher.
With the foregoing in view, the present invention has been completed. An object of the present invention is to provide a fixing member capable of suppressing the manufacturing cost of an EL device, an EL device using the fixing member and a backing substrate for the device.
With a view to attaining the above-described object, the present invention provides, in a first aspect, a fixing member for fixing a removing agent of a predetermined gas component, said fixing member comprising a sheet material equipped with a gas permeable portion which covers the removing agent at a portion other than the peripheral portion of the sheet material and an adhesion member disposed at the peripheral portion of the sheet material; in a second aspect, an EL device using the fixing member; and, in a third aspect, a backing substrate of the EL device.
The fixing member of the present invention is formed of a sheet material equipped with a gas permeable portion which covers the removing agent at a portion other than the peripheral portion of the sheet material and an adhesion member disposed at the peripheral portion of the sheet material. The fixing member can therefore be easily adhered to the inner surface of the EL device in such a manner that the removing agent is covered with the member and sandwiched between the member and the inner surface. Such a constitution does not require solidification of the removing agent, leading to a reduction in the manufacturing cost of an EL device.
When the gas permeable portion of the fixing member of the present invention is made of a porous substance composed of polytetrafluoroethylene (PTFE), its excellent heat resistance enables the stable use of the EL device even under a heated environment.
When the gas permeable portion of the fixing member of the present invention is made of a porous substance composed of a high polymer having a crystal structure, the performance of removing a predetermined gas component inside the EL device can be controlled easily, because the high polymer having a crystal structure is a material facilitating the adjustment of the pore size of the porous substance.
When the gas permeable portion of the fixing member of the present invention is made of a porous substance composed of a thermoplastic resin, its excellent processability permits easy processing of the gas permeable portion.
When a polyolefin-series resin is used as the thermoplastic resin in the fixing member of the present invention, the performance of removing a predetermined gas component inside the EL device can be controlled easily, because the polyolefin-series resin is a material facilitating the adjustment of the pore size of the porous substance. In addition, use of an inexpensive polyolefin-series resin contributes to a reduction in the manufacturing cost of the EL device. Moreover, recycling of the easily-recyclable material after use contributes to a reduction of dust.
As an adhesive used for the adhesion member of the present invention, any adhesive is usable insofar as it has a gel fraction of 70 wt. % or greater, preferably from 80 to 99 wt. %, in at least one organic solvent selected from toluene, xylene, cyclohexanone, ethanol, isopropyl alcohol, diethyl ether, hexane, carbon tetrachloride, chloroform, dimethylformamide (DMF), n-methyl-2pyrrolidone (NMP) and tetrahydrofuran, under the stable condition of the adhesive, that is, after setting when the adhesive is a setting type adhesive, after sufficient cooling when the adhesive is a hot-melt adhesive or after a sufficient time has passed since adhesion when the adhesive is a pressure-sensitive adhesive. Adhesives having a gel fraction less than 70 wt. % in any one of the above-exemplified organic solvents have considerably good compatibility therewith so that a gas of an organic substance tends to be released from the adhesive when it is integrated in the EL device. The xe2x80x9cgel fraction of an adhesivexe2x80x9d as used herein is measured as follows: first, the initial weight (W1) of an adhesive sample (about 0.1 g) is measured and then the sample is charged in a target organic solvent (about 100 ml) to immerse the former in the latter at room temperature for 168 hours (7 days). A portion which has not yet gelled is dissolved in the organic solvent. After drying the insoluble matter, the weight (W2) of the residue (gelled portion) was measured and the gel fraction is calculated based on the following equation (1):
Gel fraction (wt. %)=(W2/W1)xc3x97100xe2x80x83xe2x80x83(1) 
In the fixing member of the present invention, the thickness of the adhesion member ranges from 1 to 5000 preferably 5 to 1000 xcexcm from the viewpoint of the handling use.
When the adhesion member constituting the fixing member of the present invention is a laminate having, inside thereof, a base layer, the modulus of elasticity of the fixing member can be raised, which improves the working efficiency upon fixing of the fixing member, thereby making it possible to actualize the automated manufacture of the EL device.
In the EL device using the fixing member of the present invention, the fixing member has a simple structure formed of a sheet material and an adhesion member so that it can be adhered to the inner surface of the EL device easily, leading to a suppression of the manufacturing cost thereof.
In the EL device using the fixing member of the present invention, a removing agent is attached in advance to the backing substrate of the device, which facilitates the manufacturing work of the EL device.